He was swiftly appointed as a Government Whip when the Conservatives won the 1951 election. In December 1955 he became Government Chief Whip. Because of the convention that Whips do not speak in Parliament, he managed to keep out of the controversy over the Suez Crisis. On the announcement of Anthony Eden's resignation, Heath submitted a report on the attitude of Conservative MPs to those choosing Eden's successor which was extremely favourable to Harold Macmillan and was instrumental in securing Macmillan the job. Macmillan made him Minister of Labour after the 1959 election.

Heath was a fervent pro-European, believing in political as well as economic union. He was made Lord Privy Seal in 1960 with responsibility for the (ultimately unsuccessful) first round of negotiations to secure the UK's accession to the Common Market (as the European Community was then called). Under Sir Alec Douglas-Home he was President of the Board of Trade and oversaw the abolition of retail price maintenance.

After the Conservative Party lost the 1964 general election, Douglas-Home changed the rules to allow a ballot for party leader, and then resigned. Heath won the election in 1965, and became the youngest leader in the party's history. He retained the office despite defeat in the 1966 general election. The success of his party in the general election of 1970 surprised almost all contemporary commentators and was seen as a personal triumph.

Heath's government made only modest efforts to curtail welfare spending, though the squeeze in the education budget resulted in Margaret Thatcher's choosing to complete the process of phasing out free school milk rather than cutting back spending on the Open University. The contrast with the later actions of Thatcher's own government resulted in Heath acquiring a strongly humanitarian image.

In Northern Ireland the Heath government pushed for a peaceful settlement with the democratic political parties. The Sunningdale Agreement was produced but fiercely repudiated by many Unionists and the official Ulster Unionist Party ceased to support the Conservatives at Westminster. This was to contribute to Heath's eventual fall from power.

Heath's major achievement as prime minister was to take Britain into the European Community in 1973. Meanwhile, on the domestic front, galloping inflation led him into confrontation with some of the most powerful trade unions, and energy shortages resulted in much of the country's industry working a three-day week to conserve power. In an attempt to bolster his government, Heath called an election for February 281974. The result was inconclusive: the Conservative Party received a plurality of votes cast, but the Labour Party gained a plurality of seats due to the Ulster Unionist MPs refusing to support the Conservatives. Heath began negotations with leaders of the Liberal Party to form a coalition, but, when these failed, resigned as Prime Minister and was replaced by Harold Wilson who formed a minority government. Wilson was confirmed in office, with a wafer thin majority, in a second election in October of the same year.

As the rules of the leadership contest permitted new candidates to enter the fray in a second round of voting should the leader not be confirmed by a large enough majority, Thatcher's challenge was considered that of a stalking horse. Airey Neave as Thatcher's campaign manager was later accused of having deliberately understated her support in order to attract waverers away from Heath who lost the first ballot by 119 votes to 130 on February 4, 1975. Although Heath then withdrew from the contest, it turned out to be too late for any of his allies from his own wing of the party to overhaul Thatcher's lead. His favoured candidate, William Whitelaw, lost to Thatcher by 79 votes to 146 a week later.

Heath continued to serve as a backbench MP for the Kent constituency of Old Bexley and Sidcup until retiring from Parliament at the 2001 general election, by which time he was the longest-serving member and "Father of the House".

July1970 - Iain Macleod dies, and is succeeded as Chancellor by Anthony Barber. Geoffrey Rippon succeeds Barber as Chancellor of the Duchy of Lancaster. John Davies succeeds Rippon as Secretary for Technology.